Double ply welded plate tank wall construction

ABSTRACT

A large volume steel plate liquid storage tank including inner and outer wall plies of plate steel. Each of the inner and outer walls comprises a plurality of vertically stacked courses of wall plates and the thickness of the plates of the inner and outer plies of the tank decreases as the elevation of the courses of plates increases.

' 1 DOUBLE PLY WELDED PLATE TANK WALL CONSTRUCTION This invention relatesto an improved method of constructing large capacity liquid storage tanks such as those which may be used to store oil.

It is generally accepted that if steel plates of greater thickness than 1% inch are arc-welded together the weld joint should be heat treated to relieve internal stresses which are produced by the welding process. Thus, if a large capacity oil storage tank is to be constructed of steel plates of a thickness greater than 1% inch, each weld joint should be heat treated. However, the equipment and man hours of labor required to properly heat treat all of the welded joints of a storage tank constructed of welded steel plates involves an expense which is prohibitive. Accordingly, the capacity of storage tanks is limited to that size of tank which can be constructed to have sufficient strength without exceeding steel plate thickness of 1% inch.

Therefore, the largest capacity of straight carbon steel single ply plate tank is limited to less than 25,000 kiloliters. I

It is accordingly the main object of this invention to provide an improved method of constructing steel plate tanks in a manner not requiring heat treatment of the welded joints of the tank in order to relieve internal stresses and yet still enabling the construction of storage tanks of capacities considerably greater than 25,000 kiloliters.

Another object of this invention, in accordance with the immediately preceding object, is to provide an improved storage tank construction which may be constructed using present day accepted construction procedures. I

Another object of this invention is to provide a large capacity liquid storage tank in accordance with the preceding object and which may be either of the cone roof type or the floating roof type.

A final object of this invention to be specifically enumerated herein is to provide a liquid storage tank construction which will conform to conventional forms of manufacture, be of simple construction and easy to erect so as to provide a device that will be economically feasible, long lasting and require substantially no new skills on the part of the construction workmen erecting the tank.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.-

FIG. 1 is a fragmentary perspective viewof the wall portion of a cone roof doubleply steel plate tank constructed in accordance with the present invention;

FIG. 2 is a fragmentary perspective view of a preferred manner of securing a drainpipe through a lower portion of the tank construction illustrated in FIG. 1 and with portions of the tank construction and drainpipe being broken away and illustrated in vertical section;

FIG. 3 is a fragmentary perspectiveview illustrating a slightly modified form of outer ply construction which may be used in conjunction with the tank illustrated in FIG. 1;

FIG. 4 is an enlarged fragmentary horizontal sectional view taken substantially upon a plane passing 2 through the vertical center of the assemblage illustrated inFIG. 3;

FIG. 5 is a fragmentary perspectiveview similar to FIG. 1 but illustrating a floating roof double ply storage tank constructed in accordance with the present inventron; 1

FIG. 6 is a fragmentary enlarged perspective view of v the wall construction illustrated'in FIG. 5 illustrating that the horizontal courses of the outer ply of the tank need not be weldedtogether if the thickness of the outer ply of each course is less than one-third of the thickness of the inner ply of the same course; and

FIG. is a fragmentary perspective view similar to FIG. 6 but illustrating the manner in which the horizontal courses of the outer ply of plates may be secured together by welding if the thickness of the outer courses of plates is greater than one-third the thickness of the corresponding inner courses of plates.

Referring now more specifically to the, drawings and to FIGS. land 2' of the drawings, there may be seen a double ply tank wall construction referred to in general by the reference numeral 10 comprising the bodyof a large capacity cone roof tank. The wall construction 10 includes vertically spaced courses 12,14, 16,18, 20 and 22 of wall plates and each course includes inner and outer plates A and B.

The innerand outer plates of each course of plates are disposed in end to end abutte'd'relation and welded together as at 26. In addition, adjacent courses of inner and outer plates are welded together as at28. However, the inner and outer plates A and B of each course of plates are not welded together. As may be seen from FIGS. 1 and 7 of the drawings the thicknessof the outer plates B is greater than one-third the'thickness of the inner plates A. In this instance the inner'and outer plates A and B are not welded together and the adja cent courses of outer plates B are welded together. However, with attention invited to FIG. 6 of the drawings, in the event the outer plates B are of a thickness less than one-third the thickness of the corresponding inner plates A, the adjacent courses of outer plates B are not welded together, although the abutted ends of the outer plates B of each course are welded together.

With attention again invited to FIGS. 1, 6 and 7 of the drawings, it may be seen that the inner surfaces of each higher course of inner plates A are offset slightly outwardly of the inner surfaces .of the next lowest course of inner plates A. Further, due to the reduction in thickness of each higher course of inner and outer plates A and B, the outer surfaces of each higher course of outer plates B are inwardly offset relative to the outer surfaces of the next lower course of outer plates B. With attention now invited more specifically to FIG. 3 of the-drawings, it may be seen that when the outer plates B are of a thickness less than one-third the thickness of the-corresponding inner plates A, the adjacent endsof the outer plates B in each course of plates may be'provided with outwardly directed and backturned portions 30 secured together against separation by means of a slide type channel locking member 32. In this manner, the outer courses of outer plates B may be more readily and easily erected.

With attention now invited more specifically to FIG. 5, there may be seen'a wall construction referred to in general by the reference numeral 40 and which is simiand the inner and outer surfaces of the outer plates B are inwardly offset relative, to the outer surfaces of the inner plates A and the innerand outer surfaces of the outer plates B of the next lowest course of inner and 'outer plates A and B.

Of course, the inner plates A of the wall construction 40 are secured together at adjacent ends in each course of inner plates A and adjacent horizontal courses of inner plates A are secured together by welding. Also, because the outer plates B are of a'thickness greater than one-third the thickness of the corresponding inner plates A, not only are the adjacent ends of the outer plates B welded together but also the adjacent courses of outer plates B are welded together.

If it is desired, the method of joining the outer plates B illustrated in FIG. 3 may also be utilized to join the adjacent ends of the outer plates B used in the wall construction 40, if the thickness of the outer plates B is less than one-third the thickness of the corresponding inner plates A and the adjacent courses of outer plates B are not welded together.

With attention now invited more specifically to FIG.

2 of the drawings, it may be seen that an outlet pipe 44 may be secured through registered openings formed in inner and outer plates A and B of the tank wall construction 10 -by utilizing-inner and outer reinforcing rings secured about the pipe 44 and to the inner and outer surfaces, respectively, of the inner and outer plates A and B extending about the openings 46. in this manner, an extremely durable outlet pipe 44 is provided.

The tank wall construction 40 illustrated in H0. 5 as well as the tank wall construction illustrated in H6. l and the tank wall constructions illustrated in FIGS. 6 and 7 define circumferentially extending shoulders extending about the lower extremity of each inner course of plates A except for the lowermost course of plates A and the outer plates B may be seated on these shoulders to facilitate erecting the outer courses of outer plates B. Further, the vertical joints between the inner and outer plates A and B of each course of plates are circumferentially offset from each other and from the vertical joints between the inner and outer plates of each lower course of plates.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art. it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. A storage tank wall construction comprising'a generally cylindrical shell having inner and outer walls, said inner wall comprising a plurality of vertically stacked inner wall courses each consisting of edge upstanding and stacked circumferentially-spaced inner wall plates welded together at adjacent circumferential end edges, adjacent courses of said inner wall plates also being welded together, each course of inner wall plates above the next lower course being of slightly less thickness than the plates of the next lower course and the outer surfaces of the plates ofeach upper course being slightly inwardly displaced relative to the plates of the next lower course with the outer portions of the upper edges of the plates of the lower courses-defining outwardly projecting upwardly facing shoulders, said outer wall comprising vertically stacked outer wall courses superimposed over said inner wall courses and each consisting of edge upstanding and stacked circumferentially spaced outer wall plates whose lower edge portions rest upon the shoulders defined by thenext lower inner wall course,-the adjacent circumferential end edges of said outer wall plates being secured together, each outer course above the next lower outer wall course being of slightly less thickness than the plates of the next lower outer wall course.

2. The combination of claim 1 wherein said adjacent circumferential end edges of said outer wall plates terminate in outwardly directed upstanding flanges in turn terminating outwardly in back-turned flanges, and generally C-shaped channel members removably slidably and captively engaged with each set of corresponding outwardly directed'and back-tumed flanges retaining said adjacent circumferential end edges of said adjacent outer wall plates against separation.

3.-'The combination of claim 1 wherein said adjacent circumferential end edges of said outer wall plates are welded together.

4. The combination of claim 1 wherein the adjacent edges of adjacent courses of outer wall plates are free of rigid connection with each other.

5. The combination of claim 4 wherein the thickness of the plates of each outer wall course is less than onethird the thickness of the corresponding inner wall course plates.

6. The combination of claim 1 wherein the adjacent edges of adjacent courses of outer wall plates are welded together.

7. The combination of claim 6 wherein the thickness of the plates of each course of outer wall plates is greater than one-third the thickness of the plates of the corresponding course of inner wall plates.

8. The combination of claim 1 wherein the courses of outer wall plates are free of rigid connection with the courses of inner wall plates.

9. The combination of claim 1 wherein the thickness of each course of outer wall plates'is less than the thick- 

1. A storage tank wall construction comprising a generally cylindrical shell having inner and outer walls, said inner wall comprising a plurality of vertically stacked inner wall courses each consisting of edge upstanding and stacked circumferentially spaced inner wall plates welded together at adjacent circumferential end edges, adjacent courses of said inner wall plates also being welded together, each course of inner wall plates above the next lower course being of slightly less thickness than the plates of the next lower course and the outer surfaces of the plates of each upper course being slightly inwardly displaced relative to the plates of the next lower course with the outer portions of the upper edges of the plates of the lower courses defining outwardly projecting upwardly facing shoulders, said outer wall comprising vertically stacked outer wall courses superimposed over said inner wall courses and each consisting of edge upstanding and stacked circumferentially spaced outer wall plates whose lower edge portions rest upon the shoulders defined by the next lower inner wall course, the adjacent circumferential end edges of said outer wall plates being secured together, each outer course above the next lower outer wall course being of slightly less thickness than the plates of the next lower outer wall course.
 2. The combination of claim 1 wherein said adjacent circumferential end edges of Said outer wall plates terminate in outwardly directed upstanding flanges in turn terminating outwardly in back-turned flanges, and generally C-shaped channel members removably slidably and captively engaged with each set of corresponding outwardly directed and back-turned flanges retaining said adjacent circumferential end edges of said adjacent outer wall plates against separation.
 3. The combination of claim 1 wherein said adjacent circumferential end edges of said outer wall plates are welded together.
 4. The combination of claim 1 wherein the adjacent edges of adjacent courses of outer wall plates are free of rigid connection with each other.
 5. The combination of claim 4 wherein the thickness of the plates of each outer wall course is less than one-third the thickness of the corresponding inner wall course plates.
 6. The combination of claim 1 wherein the adjacent edges of adjacent courses of outer wall plates are welded together.
 7. The combination of claim 6 wherein the thickness of the plates of each course of outer wall plates is greater than one-third the thickness of the plates of the corresponding course of inner wall plates.
 8. The combination of claim 1 wherein the courses of outer wall plates are free of rigid connection with the courses of inner wall plates.
 9. The combination of claim 1 wherein the thickness of each course of outer wall plates is less than the thickness of the corresponding course of inner wall plates. 